If your mouse has a wheel control (usually between the left and right buttons), you can use this to change the zoom or magnification of the photograph window (works with 3D Viewer also!). Activate the photograph window, place the cursor over the photograph and roll the wheel. Rolling up increases the magnification and rolling down decreases it. The point about which the zoom takes place is the current cursor position. .
On some systems this wheel-based zoom may stop working when the scroll bars appear in the photograph window. This is a result of the mouse driver over-riding PhotoModeler. This happens only on some systems. If this behavior is annoying you can turn off wheel zoom altogether by adding this line:
WheelMouseZoom=FALSE
to the [Image] section of the PhotoModeler .ini file (see Application Data and File Locations for information on where the ini file is stored on disk).